1. Field
The following description relates to a multiple-input multiple-output (MIMO) communication system, and more particularly, to a MIMO communication system that may transmit and receive channel information using a codebook.
2. Description of Related Art
In a multiple-input multiple-output (MIMO) communication system, a transmitter and a receiver may use a codebook to transmit and receive channel information. The receiver may measure a channel formed between the transmitter and the receiver, and may generate the codebook based on the channel information. For example, the channel information may include channel direction information and channel quality information.
The transmitter may determine a precoding matrix based on channel information that is fed back from a plurality of receivers. The channel information may be used to determine a precoding matrix. The channel direction information may greatly affect the precoding matrix in a MIMO communication system. In this aspect, the channel direction information is also referred to as a precoding matrix indicator (PMI).
The codebook may include a number of codewords corresponding to a corresponding size of the codebook. For example, a 4-bit codebook may include 16 codewords. In this example, the receiver may select a single codeword from 16 codewords, and may feed back an index of the selected codeword to the transmitter as channel direction information or a PMI.